At present, for locking sashes which are both slideable and tiltable or swingable as, for example, the vertically sliding and tilting lower sashes of single hung window units the locks are mounted on top of the lower sash header to engage cooperating locking members or keepers mounted on the sill of the upper sash. Two additional pieces of hardware are provided one at each side of the lower sash to retain it against tilting. These latter locking members normally incorporate spring actuated metal plungers which engage in trackways provided in the window frame jambs to prevent unwanted sash tilting. On retraction of the plungers, the lower sash can be tilted about its bottom pivotal connections with its retaining shoes which in turn slide within trackways in the window frame jambs.
Such present hardware is expensive and the presence of a lock on top of the lower sash header limits the upward movement of the lower sash in the window frame. Similarly, if the sash is slideably horizontally, the lock on one end of the sash limits its horizontal opening movement.
By so limiting the movement of the sash, the size of the opening, that is the egress opening, available when the sash is fully open is restricted. Thus, for a given size of egress opening as required by many jurisdictions in which the window is installed, the size of the window frame must be such that it allows for the sliding movement of the sash to provide the required egress opening plus an additional size to accommodate the lock mounted on the top or end of the sash.
This requirement to accommodate the sash lock to achieve a requisite egress opening for safety adds significantly both to the window frame size and the sash area required to close the window frame adding significantly to the cost of the window installation.
It is the object of the present invention to provide a novel and extremely reliable low cost lock which will eliminate the present sash lock thereby increasing the egress opening, will provide a very positive locking of the sash in the closed position or at various open positions and will also allow for the tilting or swinging of the sash for cleaning or reglazing the window.
It is a further object of the invention to provide a lock as aforesaid which incorporates a safety mechanism which will prevent accidental unwanted tilting or swinging of the sash.
It is a further object of the invention to provide such a lock which can be produced by injection molding.